The invention relates to an inflatable protective cushion for the protection of vehicle occupants against side impact, in particular in the head and shoulder region.
Such protective cushions comprise an elongate inflatable bag that extends in the inflated condition over a large area over the region of the side windows in the vehicle from the A-column via the B-column to the C-column. The folded bag is accommodated along a roof edge situated above the side doors. A gas distribution pipe extends within and substantially over the entire length of the bag and is provided with numerous gas outlet openings which are distributed across the length of the gas distribution pipe. An end of the gas distribution pipe extendeds out from the bag and is connected to a pressurized gas source or to a gas generator. Within the bag, chambers are defined by seams, layers of fabric woven with each other or limiting straps, the form of which in the inflated bag is determined by the protective function which is aimed at. These chambers are not connected directly to the gas distribution pipe, but rather are filled indirectly through the internal pressure occurring within the bag on inflation. The inflation of the bag with the various chamber regions formed therein is a dynamic process in the course of which the pressure and volume distribution changes continuously. Through an indirect filling of the various chamber regions of the protective cushion, as is conventional, this process is scarcely able to be controlled.
The present invention provides an inflatable protective cushion wherein an optimum pressure and volume distribution can be achieved within the bag, and different chamber regions can be filled selectively. According to the invention, at least one branch line extends and is directed from the gas distribution pipe inside the inflatable bag to a portion of the bag spaced from the gas distribution pipe. Through this branch line, the respective region of the bag is filled directly, the degree of filling being determined by the length and the cross-section of the branch line. Preferably, each chamber region of the protective cushion which is to be filled in a reproducibly predetermined manner, is to have associated with it its own branch line of suitable length and suitable cross-section. As therefore all chamber regions within the bag can be filled with an optimum filling pressure and filling volume, the overall filling volume of the bag can be reduced, and an improved protective effect can nevertheless be achieved. Through such branch lines also the unfolding behavior of the bag can be improved, just as the opening behavior of the covering behind which the bag is stowed in the state of rest.
The branch line or branch lines are preferably formed from a flexible material and can therefore be folded or collapsed together with the inflatable bag of the protective cushion.
In order to ensure an introduction of gas directly into specific portions or selected chamber regions of the bag, the branch lines are each fixed in position inside the bag.